A COMPARISON OF THE SURFACE PROPERTIES OF DLC

초록

Diamond’s exellent properties, Such as its extreme hardness and high abrasion resistance, Make it an ideal material for many tribological applications. CVD diamond, available in planar film or sheet form, opens the door for design engineers and tribologists to take full advantage of diamond’s intrinsic properties in wear, solid lubrication, erosion and corrosion applications (1). Investigations have shown that CVD diamond films with only mediocre phase purity are more wear resistant than other low-wear materials. e. g. WC. AlN and Al2O3 (2). Diamond-like carbon (DLC) films have been deposited by ratio frequency plasma enhanced chemical vapour deposition (rf-PECVD) with different Ar-CH4 mixture. Nanocrystalline diamond films have been deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD), using Ar-H2-CH4 mixtures. X-ray photoelectron spectroscopy (XPS) and nanotribological investigation (by scanning force microscopy) have been used to compare the mechanical properties and structure of these films. Highly orientated and non-orientated microcrystalline diamond films and MPCVD-produced amorphous carbon (α-C) have also been studied by way of comparison. Diamond-Like Carbon shows evidence of both sp3 (diamond-like) and sp2 (graphitic) bonding in the energy loss structures of its C1s X-ray Photoelectron Spectra. Diamond shows no evidence of sp2-bonding. Diamond, as the hardest material known to man, remains the benchmark material for wear-less sliding. There is a linear relationship between its coefficient of friction and its surface roughness at both the macro-and nano-scale. For small areas and low loads such as may be found in microsystem, however, DLC may be a superior material due to the ease with which it may be deposited as a smooth film, and the inexpensive technique. Nanocrystalline diamond shows promise for small components that have complex geometries, that may not so readily be coated by the rf-PECVD technique.